What city ants can teach us about species evolution and climate change

Acorn ants are tiny. They’re not the ants you’d notice marching across your kitchen or swarming around sidewalk cracks, but the species is common across eastern North America. In particular, acorn ants live anywhere you find oak or hickory trees: both in forests and in the hearts of cities.

That’s why they’re so interesting to Sarah Diamond, a biology professor at Case Western Reserve University in Cleveland. “We’re comparing this little forest island within a city to traditional forest habitats,” she says. Specifically, she and her colleagues are looking at how well city ants can tolerate higher temperatures compared to their rural cousins. The experiment is made possible by what’s known as the urban heat island effect, which describes the tendency of the built-up infrastructure of cities — think heat-absorbing concrete and asphalt, for example — to create a hotter environment than less developed areas.